The present invention relates to a disk drive unit.
Various known disk drive units such as magnetic and optical disk drive units have read/write heads movable radially in sliding contact with information storage disks which rotate at high speed for recording signals on and reproducing signals from the information storage disks.
In some of the conventional disk drive units, the read/write heads are held in contact with information storage disks while the disks are at rest. When the disks are driven to rotate at high speed, the read/write heads are caused by an air flow generated by the high-speed rotation of the disk to float slightly from the surface of the disks. In the disk drive units of this design, the read/write head is supported on a thin cantilevered support known as the gimbal arm so as to be capable of floating under the force of the air flow.
The gimbal arm is elastically deformable quite easily. When the disk drive unit is vibrated or subject to an external shock, the gimbal arm easily flexes to allow the read/write head to hit the disk surface, thus damaging the disk surface and/or the head itself.
Most disk drive units employed as mass storage mediums are of the moving-head multiple-platter (MHMP) type in which a plurality of information storage disks are accommodated concentrically. The information storage disks contain servo infomration signals such as track information signals and synchronizing signals on equal angular positions. If one of the disks were replaced due for example to damage, then mutual synchronization would not be achieved during reproduction of stored signals from the disks.